Damage-resistant mechanical metronome



F. FRANZ Dec. 30, I969 DAMAGE-RESISTANT MECHANICAL METRONOME 2 Sheets-Sheet 1 Filed Nov. 15, 1968 INVENTOR. fFxffiW/CW [644 2 22 4 EA/T Dec. 30, 1969 F. FRANZ 3,486,323

DAMAGE-RESISTANT MECHANICAL M-ETRONOME Filed NOV. 15, 1968 2 Sheets-Sheet 2 INVENTOR. fF/Wf/F/(K [64/17 United States Patent 3,486,323 DAMAGE-RESISTANT MECHANICAL METRONOME Frederick Franz, 27 Heritage Village, Southbury, Conn. 06488 Filed Nov. 15, 1968, Ser. No. 776,085 Int. Cl. G04f 11/02 US. Cl. 58-130 Claims ABSTRACT OF THE DISCLOSURE A damage-resistant mechanical-type metronome having BACKGROUND This invention relates to metronomes of the type having a clockwork escapement which reciprocates the pen- 'dulum.

Heretofore, in metronomes of the above type there existed the possibility that the pallets and escapement wheel could be damaged during a run-down condition of the mechanism. For such condition, since the spring has unwound and the escapement wheel is idled, the teeth of the wheel sometimes obstruct the pallets. If, now, the pendulum should be forcibly swung, the interference or jamb which occurs can result in the pallets being forced out of their proper positions on the pendulum shaft, or result in other damage. This will cause the metronome to be inoperative.

SUMMARY v The above disadvantage of prior metronomes is obviated by the present invention, and therefore an object of the invention is to provide an improved damageresistant mechanical metronome having novel means for preventing damage or malfunctioning of the instrument if the pendulum is forcibly swung during obstruction of the driving pallets. This is accomplished by the provision of a yieldable spring connection between the pallets on the one hand and the pendulum on the other hand. When the pallets are obstructed, force applied to the pendulum will merely spring or cause to yield the said spring a means connection without any bending, breakage, or other damage being done. Resetting or restoring the spring connection is readily effected either manually or automatically, to restore the device to normal use.

Other features and advantages of the invention reside in the simplicity, few parts, reliability and low cost of the improved metronome, and in the small and compact construction by which the improved result is obtained.

Other features and advantages will hereinafter appear.

FIG. 1 is a front view partly in elevation and partly in vertical section of a metronome embodying the invention, shown in process of operation.

FIG. 2 is a view partly in vertical section and partly in side elevation, of the metronome of FIG. 1.

FIG. 3 is a fragmentary horizontal section taken on the I line 3-3 of FIG. 2.

FIG. 4 is a detail in front-to-rear section, showing one arrangement of spring drive between pallets and pendulum.

FIG. 5 is a vertical section taken on line 5--5 of FIG. 4.

FIG. 6 is a bottom plan view of the shaft-carried spring part of the connection of FIGS. 4 and 5.

FIG. 7 is an end elevation of the spring part of FIG. 6.

FIG. 8 is a detail in front-to-rear section, showing another arrangement of spring drive between pallets and pendulum.

FIG. 9 is a vertical section taken on line 9-9 of FIG. 8.

FIG. 10 is a detail showing the action of a stop asociated with the spring part of FIGS. 6 and 7.

The present .improved damage-resistant metronome comprises a base 10 in the form of a pyramidal-shaped housing, having a bottom edge 12 which engages the supporting surface on which the metronome rests. The present netronome is of the type which, when placed on a slopng supporting surface, will not limp; i.e. produce unequal back-and-forth movements of the pendulum due to the pendulum drive and escapement being tilted.

Carried by the base 10 is a spring motor or metronome movement 14 having a compound pendulum 16 including I a fixed weight 18 and a movable weight or slider 20 which is adjustable along the pendulum arm 22 to vary the frequency of oscillation.

The pendulum 16 is carried by an escapement shaft 24 mounted in bearing arms 26, 28 of a stamped frame, 30. The forward end 32 of the escapement shaft 24 engages a sound button or metal disk 34 carried by a sounding board portion 36 of the base-housing 10, such end being continually urged into said engagement under the action of an escapement wheel 38 alternately engaging escapement disks or pallets 40, 42 on the shaft, in the well-known manner. A special, yieldable drive is provided by the invention between the pendulum 16 and pallets 40, 42 as is described in detail further on.

The escapement wheel 38 turns with a pinion 44, both being on a shaft 46 and the pinion being driven by a main-spring gear 48 on a winding shaft 50 having a key 52 and also a back-check ratchet 54, the latter being engaged by a spring-charged pawl 56 on the frame 30. A main spring 58 drives the gear 48. The escapement pallets 40, 42 have the usual interrupted peripheries with bent, camming portions at radial cuts, whereby alternate, opposite turning moments are imparted to the shaft 24 by the escapement wheel 38 to maintain oscillation of the pendulum 16. Whenever a tooth of the escapement wheel 38 strikes one of the pallets 40, 42, the impact is transmitted through the shaft 24 to the sound button 34, causing the sounding board 36 to emit a distinct click. Thus far, the above description is that of a conventional metronome clockwork movement, which has been well known for many years to those skilled in the art.

The motor 14 which carries the pendulum 16 is suspended or movably mounted on the base 10 so as to be under the control of gravity whereby its position is automatically adjusted, providing (for different tilted positions of the base 10 within limits about an axis transverse to the direction of gravity) a fixed orientation of said movement with respect to a plane extending in a direction of gravity, said axis being contained in said plane. The axis that is transverse to the direction of gravity is in this instance parallel to the escapement shaft 24, and the reference plane that extends in the direction of gravity would be a vertical plane that includes the shaft 24. The mounting for the motor 14 maintains the motor in a given horizontal position as in FIG. 1 even though the base 10 is tilted either clockwise or counterclockwise as viewed in FIG. 1. By this arrangement the pendulum 16 and its drive mechanism involving the pallets 40, 42 and the escapement wheel 38, will not be 3 tilted either clockwise or counterclockwise from the shown position of FIG. 1, even though the base is tilted clockwise or counterclockwise within limits.

To effect this, there is a horizontal pivot shaft 62 carried by the base 10 and in turn carrying the metronome movement 14, 16 by bearing arms 64, 66 of the frame 30. The movement 14, 16 is thus pivotally suspended below the pivot shaft 62 whereby its position is under the control of gravity. The suspension arms 64, 66 are located as shown in FIGS. 1 and 2 to dispose the pivot or rocker shaft 62 vertically above and parallel to the escapement shaft 24. To effect a proper balance, a counterbalance weight 68 is mounted on the frame 30 whereby the effective center of gravity of the metronome unit 14, 16 is located vertically below the pivot shaft 62 as seen in FIG. 1.

A thrust collar 70 on the pivot shaft 62 takes the thrust force existing between the shaft 24 and sound button 34. The escapement wheel 38 turns counterclock wise as viewed in FIG. 2, thereby exerting force from left to right on the shaft 24, said shaft being axially movable within limits.

The natural period of oscillation of the metronome movement 14, 16, about the pivot shaft 62 is outside of the traditionally accepted musicians range of from 40 to 208 half oscillations per minute, thereby minimizing the tendency for the swinging pendulum 16 to cause a sympathetic oscillation of the movement 14. Also, a frictional drag exists as a result of engagement between the end 32 of the shaft 24 and the sound button 34, which frictional drag tends to damp any oscillation of the metronome movement 14, 16, about the pivot shaft 62.

The winding shaft 50 passes through a side opening 72 of the pyramidal housing (indicated generally by the numeral 74) there being adequate clearance above and below the winding shaft 50 to permit the metronome movement 14 to assume different angular positions with respect to the base 10 and housing portion 74 thereof.

The pivotal suspension of the metronome movement 14 is effective regardless of front-to-rear tilting of the base 10 within limits, as will be understood.

The periodic travel of the pendulum 16 and the vibration which a consequence of such travel results in the metronome movement 14, 16 readily overcoming any friction of its shaft suspension. It is noted that periodically the force of the shaft end 32 against the sound button 34 is relieved, whereby the metronome movement 14, 16. can always accurately respond to gravitational force and maintain a fixed orientation with respect to gravity regardless of tilting of the base 10, within the limits of the device.

The feature of preventing limping by use of a gravity controlled cloeklike movement is described and claimed in my U.S. Patent No. 3,386,327 dated June 4, 1968.

In accordance with the present invention there is provided a novel, yieldable driving connection between the pallets 40, 42, and the pendulum 16, said connection including a plurality of cooperable parts 78, 80 at least one of which yields when the pendulum is forcibly swung while a pallet is obstructed by a tooth of the wheel 38, such as can occur during a run-down condition of the spring motor.

In accomplishing this, the pendulum 16 is carried by a hub 82 which is turnable on the shaft portion 32. C01- lars 84 affixed to the shaft position the hub 82 against axial movement thereon. Rigid on the hub 82 is the part 78, constituted preferably in the form of a flat disc or plate 86 having in its periphery a notch 88 adapted to accommodate a tongue portion 90 of the cooperable tongue part 80. The part 80 is shown as comprising a leaf spring or spring finger 92 having one end affixed to a combined mounting and stop member 94 which is rigid on the shaft 24. The mounting member 94 has staked portions 96 for securement of the spring 92 in a manner that the 4 tongue 90 is resiliently or yieldably engaged in the notch 88.

With such construction, normally the drive to the pendulum 16 from the pallets 40, 42 is effected through the shaft 32, mounting member 94, tongue part or spring 92, and notched plate 86. However, ifany excessive turning force occurs between the pendulum 16 on the one hand and the pallets 40, 42 on the other hand, the spring 92 will yield and the tongue 90 thereof will be sprung out of the notch 88, this occurring before any damage or deformation of other parts of the metronome movement takes place.

To provide for restoration of the sprung driving comnection to its normal, operative condition means are provided in accordance with the invention which limits the total permissible arc of travel of the pallets to a figure which is not greater than the total maximum arc of travel of the pendulum. To effect this, the mounting member 94 has oppositely disposed ears 97 which are engageable with the undersurface of a stop member or block 98 carried by the bearing part or frame 30, FIGS. 4, 7 and 10. Such engagement'can occur after the tongue 90 has become disengaged from the notch 88, and for a condition wherein there has occurred approximately a 45 turning of the shaft 24 (FIG. 10) from a dead center position of the tongue 90 wherein it is vertically below the shaft 24. The stop member 98 limits the turning of the shaft 24 and part (including the tongue to a maximum of 90. Generally the pendulum can swing 60 in either direction from center. A pallet obstruction occurs usually with the tongue 90 at dead center. Thus, for an obstructed condition the disk 86 can shift 60 to displace the notch 88 a like amount from the tongue. Now if the pendulum is swung to the other extreme through a 120 are it will similarly turn the disk 86 more than enough to restore the tongue in the notch, which at most requires 45 plus 60 or Thus to restore a sprung connection between the parts 78, 80 the user need merely swing the pendulum between its extreme positions after first rewinding the clockwork.

It will be noted that the maximum arc of the pendulum 18 need not be 60 to each side of center, in order to enable a user to restore the yieldable driving connection. For example, if the pendulum is able to swing slightly more than 45 each side of the center, the maximum displacement of the tongue 90 from the notch 88 would be approximately 45, and the restoring movement required would then be 45, plus 45, or 90, of which the pendulum would be capable. For a greater arc of travel of the pendulum (in excess of a total of 90), it will be undesrtood that any slight overriding of the tongue 90 past the notch 88 will not defeat the restoring action since the bevel and the camming nature of the tongue will cause it to be self-centering. Thus, even a 15 override, which is preferably provided for a wide margin of safety, will still enable the tongue 90 to retrace itself and become centered in the notch 88.

Another embodiment of the invention by which there is established a yieldable spring driving connection between the pendulum 16 and the pallets 40, 42 is illustrated in FIGS. 8 and 9. In these figures there is shown a hub 102 which mounts the pallets 40, 42 and which is turnably carried by the shaft 24, said hub carrying an angle-shaped arm 104, parallel to the shaft 24. A second hub 106 is press-fitted on the shaft 24 so as to turn therewith, such hub fixedly carrying a second angle-shaped arm 108. The arms 104 and 108 have free extremity portions 110, 112 respectively, extending parallel to the shaft 24 and in spaced overlapping relation as seen in FIGS. 8 and 9. The hub 106 has an axial extension 114 around which there extends a two-layer coil spring 116 having an inner layer 118 and an outer layer 120. The two ends 122 and 124 of the coil spring 116 are generally parallel to each other and extend on opposite sides of the extremity portions 110, 112 of the angle arms 104,

108. Preferably, as shown, the extremity portions 110, 112 are provided with notches 126, 128 to accommodate and confine the spring ends 122, 124. It will be understood that the pendulum 16, for the embodiments of FIGS. 8 and 9, is fixedly carried by the shaft 24.

The pendulum 16 is rigid with the angle-shaped arm 108, these being movable with respect to the arm 104 and pallets 40, 42. Thus, relative movement is possible between the arm extremities 110, 112. However, the coil spring 116 by means of its two ends 122, 124 normally maintains the arm extremities 110, 112 in superposed and juxtaposed relation to each other as shown in FIG. 9. This is the normal condition of the yieldable driving connection, and the metronome will operate normally when the arms are held in this position. However, any excessive turning movement or force which might occur between the pendulum 16 and the pallets 40, 42 will cause the spring to yield under the force exerted by the arm extremities 110, 112. Such extremities will turn or shift with respect to each other before any damage is done to the rest of the mechanism. The spring driving connection is self-restoring in that the arms 104, 108 will be automatically reset to the proper driving positions of FIGS. 8 and 9 by the spring 116 as soon as the excessive torque or turning movement is removed between the pendulum 16 and the pallets 40, 42.

It will now be seen from the foregoing that I have provided a novel and improved damage-resistant mechanical metronome wherein the likelihood of damage or malfunctioning of the instrument is eliminated for any run-down condition of the instrument where the escapement teeth may constitute an obstruction to the pallets. For such condition, the forcing of the pendulum 16 will merely result in the spring connection yielding, preventing damage to the escapement mechanism or maladjustment of the same. In the case of the embodiment of FIGS. 8 and 9, the spring driving connection is automatically self-restoring, since the spring 116 tends to return the arms 104, 108 to the normal overlapping or aligned positions shown. With the embodiment of FIGS. 4-7, movement of the pendulum 16 by the user after first rewinding the clockwork can restore the tongue 90 in the notch 88, thereby again rendering the spring drive connection effective for oscillation of the pendulum.

Variations and modifications of the structures set forth above are possible, without departing from the spirit of the invention.

I claim:

1. A metronome comprising, in combination:

(a) a toothed escapement wheel,

(b) pallets engageable with the teeth of said wheel to be driven thereby,

(c) a pendulum, and

(d) a normally effective yieldable driving connection between the pallets and pendulum, said connection including a plurality of cooperable parts and said connection yielding when the pendulum is forcibly swung while a pallet is obstructed by a tooth in the wheel, thereby to prevent any damage from occurring.

2. A metronome as in claim 1, wherein:

(a) said yieldable driving connection comprises a notched part and a cooperable tongue part, and a yieldable mounting for one of said parts,

3. A metronome as in claim 2, and further including:

(a) a shaft carrying said pendulum and pallets,

(b) said tongue part being yieldably mounted on said shaft.

4. A metronome as in claim 3, wherein:

(a) said tongue part comprises a Spring finger which constitutes the said yieldable mounting.

5. A metronome as in claim 1, and further including:

(a) means limiting the travel of the pallets to an are which is not substantially in excess of the travel of the pendulum.

6. A metronome as in claim 5, wherein:

(a) said travel-limiting means comprises a pair of spaced-apart portions of the tongue part, and comprises a bearing part rotatably carrying said pallets and engageable with said portions of the tongue part when the pallets are turned past their operative limits.

7. A metronome as in claim 1, wherein:

(a) said yieldable driving connection comprises a pair of relatively movable arms rigid respectively with the pendulum and the pallets, and comprises a spring device for yieldably holding the arms in and returning them to a given relative position,

(b) said arms, pendulum, spring device and pallets normally moving together as a unit.

8. A metronome as in claim 7, and further including:

(a) a shaft carrying said pendulum, pallets and spring device,

(b) said spring device comprising a coil encircling the shaft,

(0) the two ends of said coil receiving the arms between them and being biased toward each other and substantially simultaneously engaging said arms to yieldably hold the latter in juxtaposition.

9. A metronome as in claim 8, wherein:

(a) the said arms are angular and have their free portions in overlapping relation,

(b) said free portions being disposed between and engaging said Spring ends.

10. A metronome as in claim 9, wherein:

(a) two hubs are carried on the shaft in axially-spaced relation,

(b) one hub being loose on the shaft and mounting the pallets and one of the angular arms in fixed relation to each other,

(c) the other hub being fixed to the shaft and fixedly mounting thereon the other arm,

(d) said pendulum being fixed on the shaft.

References Cited UNITED STATES PATENTS 705,647 7/1902 Clark 58l29 1,868,941 7/1932 Herschede et al. 58-129 3,386,327 6/1968 Franz 58-130 X FOREIGN PATENTS 1,067,427 l/l954 France.

RICHARD B. WILKINSON, Primary Examiner STANLEY A. WAL, Assistant Examiner 

